Chunhong Zhang

RESTful Web of Things API in Sharing Sensor Data

Recent development in the Web of Things (WoT) domain makes it possible to access sensor data via the web. While due to different structures and interfaces of the sensor networks, its not that easy to fully integrating their data to the web then share and reuse it later. This paper introduces a platform using RESTful Web of Things API to help share sensor data. First explains the significance and advantage of adopting RESTful style API, then points out the architecture of this platform. Later proposes the RESTful API and protocols of this platform. Finally a typical application scene of this platform is described and analyzed.

On the Disruptive Potentials in Internet of Things

Internet of things (IoT for short) has won great concerns in recent years. There will be massive changes that IoT would bring to current markets and industries. Not only some existing technologies need to be modified to support the complexity, but also some disruptive changes would happen to create new values. The potentials of disruptive innovations are analyzed and exampled from the view of technology, service, business, science and society, which features the future of IoT.

Locality-Aware Peer-to-Peer SIP

SIP (Session Initiation Protocol) is a signaling protocol widely used in multimedia communication. Recently, P2PSIP (Peer-to-Peer SIP), which combines DHT (distributed hash table) and SIP, has been proposed to overcome the drawbacks of traditional CS SIP (client/server architecture SIP). However, the introduction of DHT increases the registration overhead and, session setup overhead/latency. These problems become unbearable when P2PSIP overlay grows huge. To address these problems, we propose locality-aware P2PSIP in this paper. In the P2PSIP context, we design a locality-aware approach, which can be applied to most DHTs. This locality-aware approach reduces both DHT routing hop count and latency per DHT hop. Performance evaluation shows that registration overhead and session setup overhead/latency are reduced dramatically in locality-aware P2PSIP.

A Novel Security Mechanism to Defend Cross-Layer Security Threats in P2P Network

Peer-to-Peer overlay network provide various services for the feature of storing, discovering and locating resources efficiently. However, P2P platform raise more security-related challenges while providing more services. When P2P security mainly focusing on the security problems on Overlay, this paper first shows in-depth how can security threats intrude from underlay and penetrate into the whole P2P overlay network. A security mechanism is then provided, in which overlay can be aware of the security configuration of underlay, then provides security certificates on P2P network. Two implementation scenarios are listed. This mechanism effectively mitigates the cross-layer security threat.

Towards Autonomous System Topology Aware Relay Service Scheme

Several studies have found some properties of Internet such as Triangle Inequality Violations (TIVs). The studies have reported the existence of TIV in the Internet delay space. Triangle inequality violations that are important to peer-to-peer applications can be leveraged to build overlay routing to improve peer-to-peer performance. How to select relay nodes becomes a crucial factor to overlay routing. In this paper, we propose a scheme called Relay Service Scheme (RSS) that takes AS connecting degree and AS valley-free counts into account. We then verify the performance of the scheme with available Internet delay data set. The results demonstrate that AS connecting degree and AS valley-free counts are meaningful to relay server selection and can be utilized in building relay service to decrease about 33%-50% probing throughput in contrast to ASAP as well as improve P2P performance. It is the first scheme to pick up relay as stable and reusable servers to form a relay network. It is believed that the advantage can be used by network operator to arrange the relay servers at proper location and provide the P2P applications both good QoS performance and low overhead.

An O(1) Lookup and Decentralized Bootstrapping Peer to Peer SIP System

This paper addresses two research challenges of P2PSIP: i) call setup latency ii) decentralized bootstrapping. To optimize the call setup latency of P2PSIP, we design an O(1) lookup protocol which completes the overlay routing within 3 hops most time. We also leverage the routing table of O(1) DHT to achieve decentralized bootstrapping. Experimental results indicate that 90% of bootstrapping latency is less than 446 ms even if theres no active node within LAN. Analytic and simulation results also demonstrate the feasibility and efficiency of our proposed schemes.

Adaptor-Based Design and Implementation of Peer-to-Peer SIP

SIP (session initial protocol) is a signaling protocol widely used in IP-based multimedia communication. Recently, P2PSIP reduces the deployment and maintenance cost, as well as improves the robustness and scalability of SIP-based system. SIP, P2PSIP network will coexist in the forthcoming future. This paper focuses on the P2PSIPand its relationship with SIP. We design and implement a P2PSIP adaptor, which allows traditional SIP UAs to access to P2PSIP network. This allows P2PSIP to reuse the work in traditional SIP and makes transition from SIP to P2PSIP seamlessly. The P2PSIP adaptor can also be utilized for P2PSIP interworking by two existing interworking approaches.

Bandwidth and Efficiency of P2PSIP Based Server Farm

Peer-to-peer SIP (P2PSIP) based server farm is proposed to provide distributed solution of multimedia applications. In this paper, we focus on the bandwidth requirements of both DHT and SIP packets from the perspective of a single server node in P2PSIP based server farm to quantitatively evaluate the overhead caused by distributed architecture. Furthermore, the efficiency of server node is also studied to reflect the extent to which the number of SIP messages that a single server node can deal with drops with the increasing size of the server farm. Simulation shows that although the bandwidth requirements of DHT packets take only a small portion of the total traffic, the efficiency of the server node is influenced significantly by the DHT architecture. Hence, the P2PSIP based server farm is a feasible alternative of implementation in real networks with the optimization requirements of efficiency.